Special Containment Procedures: For safety reasons, it was decided that SCP-103-FR is to be contained according to the Beta hypothesis, as it would cause heavier damage than the Alpha hypothesis if improperly contained; hence, it should be considered true until proven otherwise.

SCP-103-FR is to be kept in an in-ground salt water pool measuring 12,000m3 in volume. The object does not require any particular surveillance, although the pool is to be fitted with a walkway, cameras, or bay windows for direct observation.

On a weekly basis, two (2) personnel with no prior experience with the object are to be selected by the Research Director to observe SCP-103-FR using the current pool's equipment. Their reactions and hypotheses are to be recorded and noted in Document 103-B.

Description: SCP-103-FR's nature cannot be confirmed with certainty. All subjects that become aware of the existence of the object will be led to hypothesize about its nature, always following two existing theories (referred to as Alpha and Beta). This effect is not limited to its observers as it seems to be based on the subjects' knowledge rather than their senses.

According to the Alpha theory, SCP-103-FR is a 1:1 scale replica of Mosasaurus hoffmannii. Subjects believing in this claim behave like they would in front of a representation of this creature and have an inclination toward assessing its realism and quality.

According to the Beta theory, SCP-103-FR is a living specimen of Mosasaurus hoffmannii. Subjects believing this claim behave like they would in front of any large, dangerous animal, showing signs of basic anxiety. Despite implications of this hypothesis, SCP-103-FR does not seem to suffer from lack of food or its confined living space. It does not display the motivation or ability to move, although this cannot be confirmed because of its effect.

The distribution of subjects between the two hypotheses is roughly 60% - 40%, favoring Alpha in a sample of two-hundred (200) individuals. Analysis of the subjects did not reveal any parameter that might influence their choices.

It is supposed that the object creates a meme inhibiting the cognitive mechanisms allowing for differentiating an object from its representation, creating confusion when considering SCP-103-FR. This confusion only appears when the subject thinks about the object, and does not affect their perception of other objects.

Addendum:

Addenda 103-1: SCP-103-FR was discovered on ██/██/████ on a beach near ███████████, ██. The following note was found in a watertight capsule nearby.